Methods for manufacturing liquid ejecting head and piezoelectric element, liquid ejecting head, liquid ejecting apparatus, and piezoelectric element

ABSTRACT

A method for manufacturing a piezoelectric element comprising forming a titanium film containing titanium; forming a platinum film containing platinum on the titanium film; forming a piezoelectric precursor film containing bismuth, lanthanum, iron and manganese on the platinum film; crystallizing the piezoelectric precursor film to form a piezoelectric layer by firing the piezoelectric precursor film in an atmosphere of an inert gas; and forming an electrode on the piezoelectric layer.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of priority to Japanese PatentApplication No. 2010-000828 filed Jan. 5, 2010, the contents of whichare hereby incorporated by reference in their entirety.

BACKGROUND

1. Technical Field

The present invention relates to a method for manufacturing a liquidejecting head that includes a pressure generating chamber communicatingwith a nozzle aperture, and a piezoelectric element changing thepressure in the pressure generating chamber and including apiezoelectric layer and electrodes applying a voltage to thepiezoelectric layer. The invention also relates to a liquid ejectinghead and a liquid ejecting apparatus.

2. Related Art

Some of the piezoelectric elements used in liquid ejecting heads have astructure in which a piezoelectric layer made of a piezoelectricmaterial capable of electromechanical conversion, such as a crystallizeddielectric material, is disposed between two electrodes. This type ofpiezoelectric element can be used as a deflection vibration modeactuator device in a liquid ejecting head. Ink jet recording heads are atypical type of liquid ejecting head. An ink jet recording head includesa vibration plate defining a part of a pressure generating chambercommunicating with a nozzle aperture through which ink droplets areejected. In the ink jet recording head, a piezoelectric element deformsthe vibration plate to apply a pressure to the ink in the pressuregenerating chamber, thereby ejecting ink droplets through the nozzleaperture. In some cases, a plurality of piezoelectric elements areprovided for respective pressure generating chambers by dividing auniform piezoelectric material layer formed over the entire surface of avibration plate into shapes corresponding to the pressure generatingchambers by photolithography.

The piezoelectric element can be made of lead zirconate titanate (PZT),as disclosed in, for example, JP-A-2001-223404.

On the other hand, piezoelectric materials containing lead-freeferroelectrics are desired from the viewpoint of environmentalprotection. An example of the lead-free piezoelectric material is BiFeO₃having a perovskite structure expressed by ABO₃. However, for example,BiFeO₃-based piezoelectric materials are less insulating and can causeleakage current. This problem can arise not only in liquid ejectingheads represented by an ink jet recording head, but also inpiezoelectric elements such as actuator devices used in otherapparatuses.

SUMMARY

An advantage of some aspects of the invention is that it provides amethod for manufacturing a liquid ejecting head including a lead-freepiezoelectric element having so high an insulation property as to reduceleakage current, and a liquid ejecting head and a liquid ejectingapparatus.

According to an aspect of the invention, a method is provided formanufacturing a liquid ejecting head including a pressure generatingchamber communicating with a nozzle aperture, and a piezoelectricelement changing the pressure in the pressure generating chamber. In themethod, a titanium film is formed. A platinum film is formed on thetitanium film. A piezoelectric precursor film containing bismuth,lanthanum, iron and manganese is formed on the platinum film. Thepiezoelectric precursor film is crystallized to form a piezoelectriclayer by firing the piezoelectric precursor film in an inert gasatmosphere. An electrode is formed on the piezoelectric layer.

This method can provide a liquid ejecting head including a lead-freepiezoelectric element having so high an insulation property as to reduceleakage current. Also, the piezoelectric layer can be highly distorted,and whose crystals can be preferentially oriented in the (100) plane.

Preferably, the inert gas is nitrogen. By performing crystallization ina nitrogen atmosphere, the resulting liquid ejecting head can include alead-free piezoelectric element having so high an insulation property asto reduce leakage current.

According to another aspect, a liquid ejecting apparatus is providedwhich includes a liquid ejecting head manufactured by the above method.Since the liquid ejecting head of the liquid ejecting apparatus includesa lead-free piezoelectric element having so high an insulation propertyas to reduce leakage current, the apparatus does not adversely affectthe environment and is so reliable as to prevent dielectric breakdown.

A method for manufacturing a piezoelectric element is also provided. Inthis method, a titanium film is formed. A platinum film is formed on thetitanium film. A piezoelectric precursor film containing bismuth,lanthanum, iron and manganese is formed on the platinum film. Thepiezoelectric precursor film is crystallized to form a piezoelectriclayer by firing the piezoelectric precursor film in an inert gasatmosphere. An electrode is formed on the piezoelectric layer. Thismethod can provide a lead-free piezoelectric element having so high aninsulation property as to reduce leakage current.

According to another aspect, a liquid ejecting head is provided whichincludes a pressure generating chamber communicating with a nozzleaperture, and a piezoelectric element changing the pressure in thepressure generating chamber. The piezoelectric element includes a firstelectrode, a piezoelectric layer containing bismuth lanthanum ferratemanganate, and a second electrode disposed on the piezoelectric layer.The first electrode includes a first titanium oxide layer containingtitanium oxide, a platinum layer containing platinum disposed on thefirst titanium oxide layer, a second titanium oxide layer containingtitanium oxide disposed on the platinum layer. The piezoelectric layeris disposed on the second titanium oxide. The structure including atitanium oxide layer, a platinum layer, a titanium oxide layer, apiezoelectric layer containing bismuth lanthanum ferrate manganate andan electrode in that order can achieve a liquid ejecting head includinga lead-free piezoelectric element having so high an insulation propertyas to reduce leakage current.

Preferably, the piezoelectric layer contains a complex oxide expressedby general formula (1):

(Bi_(1-x),La_(x))(Fe_(1-y),Mn_(y))O₃  (1)

where 0.10≦x≦0.20 and 0.01≦y≦0.09

Since ABO₃-type complex oxides expressed by general formula (1) canexhibit ferroelectric characteristics, the liquid ejecting head caninclude a lead-free piezoelectric element allowing easy control of thedistortion. The piezoelectric element can easily control the size ofdroplets ejected.

Preferably, the piezoelectric layer exhibits a powder X-ray diffractionpattern measured at φ=ψ=0° in which the area intensity of the peakderived from ABO₃ structures observed in 20°<2θ<25° is at least 90% thatof the total area intensity of peaks derived from ABO₃ structuresobserved in 20°<2θ<50°. Such a piezoelectric layer provides superiorpiezoelectric characteristics.

According to another aspect of the invention, a liquid ejectionapparatus including the above-described liquid ejection head isprovided. Since the liquid ejecting head of the liquid ejectingapparatus includes a lead-free piezoelectric element having so high aninsulation property as to reduce leakage current, the apparatus does notadversely affect the environment and is so reliable as to preventdielectric breakdown.

A piezoelectric element also provided which includes a first electrode,a piezoelectric layer containing bismuth lanthanum ferrate manganate,and a second electrode disposed on the piezoelectric layer. The firstelectrode includes a first titanium oxide layer containing titaniumoxide, a platinum layer containing platinum disposed on the firsttitanium oxide, and a second titanium oxide layer containing titaniumoxide disposed on the platinum layer. The piezoelectric layer isdisposed on the second titanium oxide layer. This structure can providea lead-free piezoelectric element having so high an insulation propertyas to reduce leakage current.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will be described with reference to the accompanyingdrawings, wherein like numbers reference like elements.

FIG. 1 is a schematic exploded perspective view of a recording headaccording to an embodiment of the invention.

FIG. 2 is a plan view of the recording head according to the embodiment.

FIG. 3A is a sectional view of the recording head according to theembodiment, and FIG. 3B is a fragmentary enlarged sectional view of amain portion of the recording head shown in FIG. 3A.

FIG. 4 is a P-V curve of Sample 1.

FIG. 5 is a P-V curve of Sample 2.

FIG. 6 is a P-V curve of Sample 3.

FIG. 7 is a P-V curve of Sample 4.

FIG. 8 is a P-V curve of Sample 5.

FIG. 9 is a P-V curve of Sample 6.

FIG. 10 is a P-V curve of Sample 7.

FIG. 11 is a P-V curve of Sample 8.

FIG. 12 is a P-V curve of Sample 9.

FIG. 13 is a P-V curve of Sample 10.

FIG. 14 is a P-V curve of Sample 11.

FIG. 15 is a P-V curve of Sample 12.

FIG. 16 is a P-V curve of Sample 13.

FIG. 17 is a P-V curve of Sample 14.

FIG. 18 is a P-V curve of Sample 15.

FIGS. 19A and 19B are sectional views showing a manufacturing process ofthe recording head according to the embodiment.

FIGS. 20A to 20C are sectional views showing the manufacturing processof the recording head according to the embodiment.

FIGS. 21A and 21B are sectional views showing the manufacturing processof the recording head according to the embodiment.

FIGS. 22A to 22C are sectional views showing the manufacturing processof the recording head according to the embodiment.

FIGS. 23A and 23B are sectional views showing the manufacturing processof the recording head according to the embodiment.

FIG. 24 is a plot of P-V curves of the Example and Comparative Example1.

FIG. 25 is a plot of P-V curves of the Example and Comparative Example2.

FIG. 26 is a plot of P-V curves of the Example and Comparative Example3.

FIG. 27 is a plot of S-V curves of the Example and Comparative Example1.

FIG. 28 is a plot of S-V curves of the Example and Comparative Example3.

FIG. 29 is a plot of SIMS analysis results of the Example andComparative Example 1.

FIG. 30 is a plot of SIMS analysis results of the Example.

FIG. 31 is a plot of SIMS analysis results of Comparative Example 2.

FIG. 32 is X-ray diffraction patterns of the Example and ComparativeExamples.

FIG. 33 is X-ray diffraction patterns of the Example and ComparativeExamples.

FIG. 34 is a plot showing tunnel emission mechanisms of the Example andComparative Example 1.

FIG. 35 is a plot of I-V curves of the Example and Comparative Example1.

FIG. 36 is a schematic view of a recording apparatus according to anembodiment of the invention.

DESCRIPTION OF EXEMPLARY EMBODIMENTS

FIG. 1 is a schematic exploded perspective view of an ink jet recordinghead that is a type of liquid ejecting head manufactured by a methodaccording to an embodiment of the invention. FIG. 2 is a plan view ofthe ink jet recording head shown in FIG. 1. FIG. 3A is a sectional viewtaken along line III-III in FIG. 2, and FIG. 3B is an enlarged view of amain part of FIG. 3A.

A flow channel substrate 10 is made of monocrystalline silicon, and asilicon dioxide elastic film 50 is formed on one surface of the flowchannel substrate 10, as shown in FIGS. 1 to 3.

The flow channel substrate 10 has a plurality of pressure generatingchambers 12 arranged in parallel in the direction of their widths. Theflow channel substrate 10 also has a communicating section 13 therein ina region to the outside of the pressure generating chambers 12 in theirlongitudinal direction. The communicating section 13 communicates withthe pressure generating chambers 12 through their respective ink supplychannels 14 and communication paths 15. The communicating section 13communicates with a reservoir section 31 formed in a protectivesubstrate (described later) to define part of a reservoir acting as acommon ink chamber of the pressure generating chambers 12. Each inksupply channel 14 has a smaller width than the pressure generatingchamber 12, so that the flow channel resistance of the ink delivered tothe pressure generating chamber 12 from the communicating section 13 iskept constant. Although the ink supply channels 14 are formed bynarrowing the flow channels from one side, in the present embodiment,the flow channels may be narrowed from both sides. Alternatively, theink supply channels 14 may be formed by reducing the depth of the flowchannels, instead of narrowing the flow channels. In the presentembodiment, the flow channel substrate 10 has liquid flow channelsincluding the pressure generating chambers 12, the communicating section13, the ink supply channels 14 and the communication paths 15.

The flow channel substrate 10 is joined with a nozzle plate 20 at theopen side thereof with an adhesive, thermal fusion film or the like. Thenozzle plate 20 has nozzle apertures 21 communicating with end portionsof the respective pressure generating chambers 12 opposite to the inksupply channels 14. The nozzle plate 20 can be made of, for example,glass-ceramic, monocrystalline silicon or stainless steel.

On the other hand, an elastic film 50 is formed over the other side,opposite to the open side, of the flow channel substrate 10, and aninsulating film 55 is formed of, for example, zirconium oxide on theelastic film 50.

Furthermore, piezoelectric elements 300 are formed on the insulatingfilm 55. Each piezoelectric element 300 includes a first electrode 60, apiezoelectric layer 70 having a small thickness of 2 μm or less,preferably 0.3 to 1.5 μm, and a second electrode 80. The piezoelectricelement 300 mentioned herein refers to the portion including the firstelectrode 60, the piezoelectric layer 70 and the second electrode 80. Ingeneral, either electrode of the piezoelectric element 300 acts as acommon electrode, and the other electrode and the piezoelectric layer 70are formed for each pressure generating chamber 12 by patterning.Although in the present embodiment, the first electrode 60 acts as thecommon electrode of the piezoelectric elements 300 and the secondelectrode 80 is provided as discrete electrodes of the piezoelectricelements 300, the functions of the first and second electrodes may bereversed for the sake of convenience of the driving circuit and wiring.

An actuator device mentioned herein is defined by a combination of thepiezoelectric element 300 and a vibration plate that can be displaced bythe operation of the piezoelectric element 300. In the presentembodiment, the vibration plate includes the elastic film 50, theinsulating film 55 and the first electrode 60. However, the vibrationplate is not limited to this structure, and, for example, only the firstelectrode 60 may act as the vibration plate without using the elasticfilm 50 or the insulating film 55. The piezoelectric element 300 maydouble as a vibration plate in substance.

In the present embodiment, the first electrode 60 includes a firsttitanium oxide layer 61 containing titanium oxide disposed on theinsulating film 55, a platinum layer 62 containing platinum disposed onthe first titanium oxide layer 61, and a second titanium oxide layer 63containing titanium oxide disposed on the platinum layer 62, as shown inFIG. 3B. The conductivity of the first electrode 60 mainly depends onthe platinum layer 62. On the other hand, the first and second titaniumoxide layers 61 and 63 may have low conductivities, and may be formeddiscontinuously, for example, in an island manner. Preferably, thesecond titanium oxide layer 63 has a thickness of 3 nm or less. A secondtitanium oxide layer 63 of more than 3 nm in thickness has a lowdielectric constant and may reduce the piezoelectric characteristicsaccordingly. By forming a second titanium oxide layer to a thickness of3 nm or less, the piezoelectric characteristics can be enhanced.

The piezoelectric layer 70 is made of a piezoelectric materialcontaining bismuth lanthanum ferrate manganate, that is, an ABO₃-typecomplex oxide containing bismuth (Bi), lanthanum (La), iron (Fe) andmanganese (Mn). The A site of the ABO₃ structure, or perovskitestructure, has 12 oxygen ligands, and the B site has 6 oxygen ligands toform an octahedron. Bi and La are present in the A site, and Fe and Mnare present in the B site.

The piezoelectric element of the present embodiment is produced byforming a platinum film being a precursor of the platinum layer 62 on atitanium base layer, forming a piezoelectric precursor film containingbismuth, lanthanum, iron and manganese on the platinum film, andcrystallizing the piezoelectric precursor film by firing it. Thisprocess will be described in detail later. In this process, the titaniumof the titanium base layer diffuses into the piezoelectric layer 70through platinum grain boundaries while the piezoelectric precursor filmis crystallized. Thus a highly insulating piezoelectric layer 70 can beformed. In addition, when this piezoelectric element is used as apiezoelectric actuator, it can produce a large distortion. Thepiezoelectric layer 70 can exhibit a diffraction pattern in which thearea intensity of the peak derived from ABO₃ structures observed in0°<2θ<25° is at least 90% that of the total area intensity of peaksderived from ABO₃ structures observed in 20°<2θ<50°. This means that thepiezoelectric layer is oriented preferentially in the (100) plane.

The amount of titanium diffused into the piezoelectric layer 70 is notparticularly limited in the above process, but the titanium content inthe piezoelectric layer 70 is preferably 5% by mass or less. Anexcessively high titanium content may adversely affect the piezoelectricproperties other than the insulation property. In the presentembodiment, even a piezoelectric layer 70 containing titanium as low as0.1% to 0.5% by mass can be sufficiently insulating.

Preferably, the piezoelectric layer 70 containing bismuth (Bi),lanthanum (La), iron (Fe) and manganese (Mn) has a composition expressedby general formula (1):

(Bi_(1-x),La_(x))(Fe_(1-y),Mn_(y))O₃  (1)

where 0.10≦x≦0.20 and 0.01≦y≦0.09

The piezoelectric layer 70 having a composition expressed by generalformula (I) can be ferroelectric. The use of a ferroelectricpiezoelectric layer 70 allows easy control of the distortion.Accordingly, when the piezoelectric element is used in a liquid ejectinghead, the size of ink droplets ejected can be easily controlled. ABO₃complex oxides containing Bi, La, Fe and Mn exhibited differentcharacteristics and were ferroelectric, antiferroelectric orparaelectric, depending on the composition. Piezoelectric elementsamples (Samples 1 to 18) having different compositions expressed bygeneral formula (1) were prepared, and triangular waves of 25 V or 30 Vwere applied to the samples to obtain their P (polarization)-V (voltage)relationship. The results are shown in FIGS. 4 to 18, and thecompositions of the samples are shown in the Table below. Samples 16 to18 caused too large leakage to be measured, and could not be used aspiezoelectric materials. As shown in FIGS. 4 to 14, each of Samples 1 to11, whose compositions satisfy 0.10≦x≦0.20 and 0.01≦y≦0.09, exhibitedhysteresis loops distinctive of ferroelectric materials. Since thedistortion of the Samples 1 to 11 varies linearly with the appliedvoltage, the distortion can be easily controlled. On the hand, Samples12 to 14, whose compositions of general formula (I) did not satisfy0.10≦x≦0.20 or 0.01≦y≦0.09, exhibited double hysteresis loopsdistinctive of antiferroelectric materials that have two hysteresisshapes respectively in a positive electric field and a negative electricfield, as shown in FIGS. 15 to 17, and were therefore antiferroelectric.Sample 15, whose composition is also outside the desired ranges, wasparaelectric as sown in FIG. 18. Samples 16 to 18 caused large leakageand could not be used as piezoelectric materials, as mentioned above.Thus, Samples 12 to 18 were not all ferroelectric.

TABLE x Y Sample 1 0.10 0.03 Sample 2 0.10 0.05 Sample 3 0.10 0.09Sample 4 0.14 0.05 Sample 5 0.17 0.03 Sample 6 0.18 0.03 Sample 7 0.200.01 Sample 8 0.20 0.02 Sample 9 0.19 0.03 Sample 10 0.19 0.04 Sample 110.19 0.05 Sample 12 0.21 0.03 Sample 13 0.24 0.05 Sample 14 0.29 0.05Sample 15 0.48 0.05 Sample 16 0.20 0.00 Sample 17 0.10 0.00 Sample 180.00 0.00

If the piezoelectric layer is made of an antiferroelectric material inwhich spontaneous polarizations are arranged antiparallel to adjacentones, that is, if the piezoelectric layer is made of a material that canexhibit electric field-induced phase transition, electric field-inducedphase transition occurs in the piezoelectric layer to produce a largerdistortion when a certain voltage or more is applied. Thus, theantiferroelectric piezoelectric layer can produce a larger distortionthan ferroelectric materials. However, it cannot operate unless thecertain voltage or more is applied, and the distortion does not varylinearly with the voltage. The electric field-induced phase transitionrefers to a phase transition occurring in an electric field, and may bea transition from an antiferroelectric phase to a ferroelectric phase ora transition from a ferroelectric phase to an antiferroelectric phase.The ferroelectric phase is a state in which polarization axes extend inthe same direction, and the antiferroelectric phase is a state in whichpolarization axes are arranged in antiparallel to adjacent ones. Forexample, a phase transition from an antiferroelectric phase to aferroelectric phase is that antiparallel axes of the antiferroelectricphase are aligned in the same direction by rotation of 180° to turn intoa ferroelectric phase. Such an electric field-induced phase transitionexpands or contracts the lattices to cause distortion. This distortionrefers to phase transition distortion caused by electric field-inducedphase transition. Substances in which such electric field-induced phasetransition can occur refer to antiferroelectrics. Hence, thepolarization axes of an antiferroelectric are antiparallel with noelectric field applied, but are aligned in the same direction byapplying an electric field. The P-V curve (relationship between thepolarization P and the voltage V) of such an antiferroelectric materialshows a double hysteresis loop having two hysteresis shapes respectivelyin a positive electric field and in a negative electric field. In theP-V curve, a transition from a ferroelectric phase to anantiferroelectric phase or a transition from an antiferroelectric phaseto a ferroelectric phase occurs in regions where the polarization issharply changed.

On the other hand, ferroelectrics do not exhibit double hysteresis P-Vcurves, unlike antiferroelectrics, and the distortion varies linearlywith the applied voltage in a state where the polarization is aligned.Accordingly, the distortion of ferroelectrics can be easily controlled,and the size of droplets ejected can be easily controlled accordingly.Consequently, a single piezoelectric element can generate two types ofvibration: small amplitude vibration generating microvibration; andlarge amplitude vibration producing a large excluded volume.

It is preferable that the piezoelectric layer 70 of the presentembodiment exhibits a powder X-ray diffraction pattern having peaks ofboth ferroelectric phases having ferroelectricity and antiferroelectricphases having antiferroelectricity. By using a piezoelectric layer 70 inthe morphotropic phase boundary (MPB) between antiferroelectric andferroelectric phases, exhibiting peaks of ferroelectric phases andantiferroelectric phases, a piezoelectric element producing a largedistortion can be provided. Preferably, the piezoelectric layer 70contains a complex oxide expressed by general formula (I) satisfying therelationship 0.17≦x≦0.20, preferably 0.19≦x≦0.20. Complex oxides in thisrange exhibit powder X-ray diffraction spectra simultaneously havingpeaks of ferroelectric phases and peaks of antiferroelectric phases, asdescribed in the Example later. Hence, these materials are in the MPBbetween antiferroelectric and ferroelectric phases, and thus, thepiezoelectric element including such a piezoelectric layer can produce alarge distortion.

The second electrode 80 of each piezoelectric element 300 is connectedwith a lead electrode 90 made of, for example, gold (Au) extending fromone end at the ink supply channel 14 side of the second electrodes 80 tothe surface of the insulating film 55.

A protective substrate 30 having a reservoir section 31 defining atleast part of a reservoir 100 is joined to the flow channel substrate 10having the piezoelectric elements 300 with an adhesive 35 so as to coverthe first electrodes 60, the insulating film 55 and the lead electrodes90. The reservoir section 31 passes through the thickness of theprotective substrate 30 and extends along the widths of the pressuregenerating chambers 12. Thus, the reservoir section 31 communicates withthe communicating section 13 of the flow channel substrate 10 to formthe reservoir 100 acting as the common ink chamber of the pressuregenerating chambers 12. The communicating section 13 of the flow channelsubstrate 10 may be divided for each pressure generating chamber 12, andonly the reservoir section 31 may serve as the reservoir. Alternatively,the flow channel substrate 10 may have only the pressure generatingchambers 12, and the reservoir and ink supply channels 14 communicatingwith the respective pressure generating chambers 12 are formed in amember, such as the elastic film 50 or the insulating film 55, betweenthe flow channel substrate 10 and the protective substrate 30.

Piezoelectric element-protecting section 32 is formed in the region ofthe protective substrate 30 corresponding to the piezoelectric elements300. The Piezoelectric element-protecting section 32 has a space so thatthe piezoelectric elements 300 can operate without interference. Thespace of the piezoelectric element-protecting section 32 is intended toensure the operation of the piezoelectric elements 300, and may or maynot be sealed.

Preferably, the protective substrate 30 is made of a material havingsubstantially the same thermal expansion coefficient as the flow channelsubstrate 10, such as glass or ceramic. In the present embodiment, theprotective substrate 30 is made of the same monocrystalline silicon asthe flow channel substrate 10.

The protective substrate 30 has a through hole 33 passing through thethickness of the protective substrate 30. The respective lead electrodes90 extending from the piezoelectric elements 300 are exposed in thethrough hole 33.

A driving circuit 120 is secured on the protective substrate 30 to drivethe piezoelectric elements 300 arranged in parallel. The driving circuit120 may be a circuit board, a semiconductor integrated circuit (IC) orthe like. The driving circuit 120 is electrically connected to each leadelectrode 90 with an electroconductive connection wire 121, such as abonding wire.

Furthermore, a compliance substrate 40 including a sealing film 41 and afixing plate 42 is joined on the protective substrate 30. The sealingfilm 41 is made of a flexible material having a low rigidity, and sealsone side of the reservoir section 31. The fixing plate 42 is made of arelatively hard material. The portion of the fixing plate 42 opposingthe reservoir 100 is completely removed in the thickness direction toform an opening 43; hence the reservoir 100 is closed at one end onlywith the flexible sealing film 41.

The ink jet recording head I of the present embodiment draws an inkthrough an ink inlet connected to an external ink supply means (notshown). The ink is delivered to fill the spaces from the reservoir 100to the nozzle apertures 21. Then, the ink jet recording head I applies avoltage between the first electrode 60 and each second electrode 50corresponding to the pressure generating chambers 62, according to therecording signal from the driving circuit 120. Thus, the elastic film50, the insulating film 55, the first electrode 60 and the piezoelectriclayers 70 are deflected to increase the internal pressure in thepressure generating chambers 12, thereby ejecting the ink from thenozzle apertures 21.

A method for manufacturing the ink jet recording head according to thefirst embodiment will be described with reference to FIG. 19A to 23B.FIGS. 19A to 23B are sectional views of a pressure generating chambertaken in the longitudinal direction.

As shown in FIG. 19A, a silicon dioxide (SiO₂) film intended to be anelastic film 50 is formed on the surface of a silicon wafer 110 for aflow channel substrate by thermal oxidation or the like. Then, aninsulating film 55 is formed of, for example, zirconium oxide on theelastic film 50 (silicon dioxide film) by reactive sputtering, thermaloxidation or the like, as shown in FIG. 19B.

Then, a titanium film 56 is formed on the insulating film 55 by DCsputtering, ion sputtering or the like, as shown in FIG. 20A.Subsequently, a platinum film 57 is formed on the titanium film 56 by DCsputtering or the like, followed by patterning. By appropriatelyadjusting the thicknesses, heating conditions or other conditions of thetitanium film 56 and the platinum film 57, the amount of titaniumdiffused during the crystallization of the piezoelectric precursor filmdescribed below can be adjusted.

Then, a piezoelectric layer 70 is formed on the platinum film 57. Thepiezoelectric layer 70 may be formed by any method without particularlimitation. For example, metal-organic decomposition (MOD) may beapplied, in which a solution containing an organic metal compounddissolved or dispersed in a solvent is applied onto the platinum film57, and the coating of the solution is dried and then fired to form ametal oxide piezoelectric layer 70. The piezoelectric layer 70 may beformed by a liquid process or a solid process without being limited toMOD. Exemplary processes include a sol-gel method, laser ablation,sputtering, pulsed laser deposition (PLD), CVD, and aerosol deposition.

More specifically, the piezoelectric layer 70 is formed as follows.First, as shown in FIG. 20B, a sol or MOD solution (precursor solution)containing organic metal compounds containing bismuth, lanthanum, ironand manganese in a desired proportion is applied onto the platinum film57 by spin coating or the like to form a piezoelectric precursor film 71(coating).

The precursor solution is prepared by mixing organic metal compoundsrespectively containing bismuth, lanthanum, iron and manganese so thatthe metals have desired mole fractions, and dissolving or dispersing themixture in alcohol or other organic solvents. Organic metal compoundscontaining bismuth, lanthanum, iron or manganese include metalalkoxides, organic acid salts, and β-diketone complexes. For example,the organic metal compound containing bismuth may be bismuth2-ethylhexanoate. For example, the organic metal compound containinglanthanum may be lanthanum 2-ethylhexanoate. For example, the organicmetal compound containing iron may be iron 2-ethylhexanoate. Forexample, the organic metal compound containing manganese may bemanganese 2-ethylhexanoate.

Subsequently, the piezoelectric precursor film 71 is heated to apredetermined temperature to be dried for a certain time (drying). Then,the dried piezoelectric precursor film 71 is heated to a predeterminedtemperature and allowed to stand for a certain time to be degreased(degreasing). The degreasing mentioned herein is performed to convertorganic components in the piezoelectric precursor film 71 into, forexample, NO₂, CO₂ or H₂O and thus to remove the organic components. Thedrying and degreasing may be performed in any atmosphere withoutparticular limitation, and may be performed in the air or an inert gasatmosphere.

Then, as shown in FIG. 20C, the piezoelectric precursor film 71 isheated to a predetermined temperature, for example, to about 600 to 700°C., and allowed to stand for a certain time in an inert gas atmosphere,thus being crystallized to form a piezoelectric film 72 (firing).

The drying, the degreasing and the firing can be performed with aheating apparatus, such as a rapid thermal annealing (RTA) apparatususing an infrared lamp for heating or a hot plate.

Then, as shown in FIG. 21A, a resist layer having a predetermined shape(not shown) is formed on the piezoelectric film 72, and thepiezoelectric film 72 and the first electrode 60 are simultaneouslypatterned using the resist layer as a mask so that their sides areinclined.

After removing the resist layer, the sequence of coating, drying anddegreasing, or the sequence of coating, drying, degreasing and firing isrepeated according to the desired thickness. Thus a piezoelectric layer70 having a desired thickness including a plurality of piezoelectricfilms 72 is formed, as shown in FIG. 21B. If, for example, a coatingformed by a single coating operation has a thickness of about 0.1 μm,the piezoelectric layer 70 including 10 piezoelectric films 72 has atotal thickness of about 1.1 μm. Although a plurality of piezoelectricfilms 72 are layered in the present embodiment, the piezoelectric layer70 may include only a single piezoelectric film 72.

In this operation for forming the piezoelectric layer 70, the titaniumin the titanium film 56 formed at the flow channel substrate 10 side ofthe platinum film 57 intended to be the first electrode 60 is diffusedby firing the piezoelectric precursor film 71 to crystallize it in aninert gas atmosphere. For example, the titanium is diffused to thepiezoelectric film 72, and consequently, the resulting piezoelectriclayer 70 contains titanium. Probably, the titanium in the titanium film56 diffuses into the piezoelectric layer 70 through the grain boundariesin the platinum film 57 between the titanium film 56 and thepiezoelectric layer 70.

As described above, by heating the piezoelectric precursor film 71 onthe platinum film 57 overlying the titanium film 56 in an inert gasatmosphere to crystallize the precursor film 71, the titanium in thetitanium film 56 is diffused. Consequently, the insulation is increaseto reduce the occurrence of leakage current. In addition, the distortioncan be increased. Furthermore, the resulting piezoelectric layer 70 canexhibit a diffraction spectrum in which the area intensity of the peakderived from ABO₃ structures observed in 20°<2θ<25° is at least 90% thatof the total area intensity of peaks derived from ABO₃ structuresobserved in 20°<2θ<50°. This means that the piezoelectric layer 70 isoriented preferentially in the (100) plane.

The platinum film 57 containing platinum is turned into the platinumlayer 62 through the crystallization of the piezoelectric precursor film71, and the resulting platinum layer 62 may contain titanium or titaniumoxide, depending on the degree of the diffusion of titanium. Inaddition, in the present embodiment, the diffused titanium forms asecond titanium oxide layer 63 containing titanium oxide between theplatinum layer 62 and the piezoelectric layer 70. Also, the titanium notdiffused from the titanium film 56 at the flow channel substrate 10 sideof the platinum layer 62 forms a first titanium oxide layer 61containing titanium oxide. However, the first titanium oxide layer 61 orthe second titanium oxide layer 63 may be hardly formed, depending onthe degree of the diffusion of titanium. Although, in the presentembodiment, titanium is diffused up to the inside of the piezoelectriclayer 70, the piezoelectric layer 70 does not necessarily containtitanium as long as the titanium diffuses up to the interface betweenthe piezoelectric layer 70 and the platinum layer 62. The amount oftitanium diffused during the crystallization of the piezoelectricprecursor film 71 can be adjusted by controlling the firing temperatureand the firing time.

The inert gas atmosphere mentioned herein refers to an atmosphere of anoble gas, such as helium or argon, an inert gas, such as nitrogen, or amixture of these gases. For heating, the heating apparatus may be purgedwith an inert gas, or the inert gas may be allowed to flow in theheating apparatus. The concentration of the inert gas is not necessarily100%, as long as titanium can diffuse from the titanium film 56 at theflow channel substrate 10 side of the platinum film 57. For example, theinert gas may contain 20% or less of oxygen.

After the piezoelectric layer 70 is formed, a second electrode 80 isformed of platinum on the piezoelectric layer 70 by sputtering or thelike, as shown in FIG. 22A, and the piezoelectric layer 70 and thesecond electrode 80 are simultaneously patterned to form piezoelectricelements 300, each including the first electrode 60, the piezoelectriclayer 70 and the second electrode 80, in the regions corresponding tothe pressure generating chambers 12. The patterning of the piezoelectriclayer 70 and the second electrode 80 can be performed at one time by dryetching through a resist layer (not shown) having a predetermined shape.After this operation, post-annealing may be performed at a temperaturein the range of 600 to 700° C., if necessary. Thus favorable interfacescan be formed between the piezoelectric layer 70 and the first electrode60 and between the piezoelectric layer 70 and the second electrode 80,and the crystallinity of the piezoelectric layer 70 can be enhanced.

Then, as shown in FIG. 22B, a film is formed of, for example, gold (Au),over the entire surface of the flow channel substrate wafer 110, and ispatterned into lead electrodes 90 for each piezoelectric element 300through a mask pattern (not shown) made of, for example, resist.

Then, as shown in FIG. 22C, after a silicon protective substrate wafer130 for a plurality of protective substrates 30 is bonded to thepiezoelectric element 300 side of the flow channel substrate wafer 110with an adhesive 35, the thickness of the flow channel substrate wafer110 is reduced.

Then, a film for a mask 52 is formed on the surface of the flow channelsubstrate wafer 110 opposite to the protective substrate wafer 130 andis patterned into a mask 52 having a predetermined shape, as shown inFIG. 23A.

Subsequently, as shown in FIG. 23B, the flow channel substrate wafer 110is subjected to anisotropic etching (wet etching) using an alkalinesolution, such as KOH, through the mask 52, to form the pressuregenerating chambers 12 corresponding to the piezoelectric elements 300,the communicating section 13, the ink supply channels 14 and thecommunication paths 15 therein.

Then, unnecessary outer portions of the flow channel substrate wafer 110and the protective substrate wafer 130 are cut off by, for example,dicing. Subsequently, a nozzle plate 20 having nozzle apertures 21therein is joined to the surface of the flow channel substrate wafer 110opposite the protective substrate wafer 130 after the mask 52 have beenremoved, and a compliance substrate 40 is joined to the protectivesubstrate wafer 13. The flow channel substrate wafer 110 joined withother substrates together is cut into chips, each including a flowchannel substrate 10 and other members. Thus an ink jet recording head Iof the present embodiment is produced.

The invention will be further described in detail with reference to theExample below. However, the invention is not limited to the followingExample.

EXAMPLE

First, a silicon dioxide film was formed on a silicon substrate bythermal oxidation. Then, a zirconium oxide film was formed to athickness of 400 nm on the silicon dioxide film by radio frequency (RF)sputtering. Subsequently, a titanium film was formed to a thickness of20 nm on the zirconium oxide film by direct current (DC) sputtering.Then, a platinum film was formed to a thickness of 130 nm on thetitanium film by DC sputtering.

Subsequently, a piezoelectric layer was formed on the platinum film byspin coating in the following process. First, a precursor solution wasprepared by mixing solutions of bismuth 2-ethylhexanoate, lanthanum2-ethylhexanoate, iron 2-ethylhexanoate and manganese 2-ethylhexanoatein xylene or octane in a predetermined proportion. The precursorsolution was dropped onto the platinum film on the substrate, and thesubstrate was spun at 500 rpm for 5 seconds and then at 1500 rpm for 30seconds to form a piezoelectric precursor film (coating). The resultingpiezoelectric precursor film was dried and degreased at 350° C. in theair for 3 minutes (drying and degreasing). After repeating the sequenceof the coating and the drying and degreasing twice, the precursor filmwas fired in a heating apparatus in which nitrogen was flowing at a flowrate of 500 cc/min, by rapid thermal annealing (RTA) at 650° C. for 2minutes (firing). This operation of firing together after repeating thesequence twice of the coating and the drying and degreasing wererepeated three times. The resulting films were fired in a heatingapparatus in which nitrogen was flowing at a flow rate of 500 cc/min, byRTA at 650° C. for 5 minutes, and thus a piezoelectric layer having athickness of 450 nm was formed through a total of six times of coating.

Then, a platinum film was formed to a thickness of 100 nm as a secondelectrode on the piezoelectric layer by DC sputtering, and the resultingstructure was fired in a heating apparatus in which nitrogen was flowingat a flow rate of 500 cc/min, by RTA at 650° C. for 5 minutes. Thus apiezoelectric element was completed which included a piezoelectric layermade of an ABO₃-type complex oxide having a composition expressed bygeneral formula (I) wherein x=0.19 and y=0.03, and further containingtitanium.

Comparative Example 1

A piezoelectric element was produced by the same operation as in theExample except that RTA was performed in a heating apparatus in whichoxygen was flowing at a flow rate of 500 cc/min instead of nitrogenflowing at a flow rate of 500 cc/min.

Comparative Example 2

A piezoelectric element was produced by the same operation as in theExample except that a titanium oxide film was formed on the zirconiumoxide film, instead of the titanium film, and the piezoelectric layerwas formed over the titanium oxide film.

Comparative Example 3

A piezoelectric element was produced by the same operation as in theExample except that the piezoelectric layer was formed on an iridiumfilm formed to a thickness of 20 nm on the platinum film by DCsputtering.

Comparative Example 4

A piezoelectric element was produced by the same operation as in theExample except that a titanium oxide film was formed on the zirconiumoxide film, instead of the titanium film so that the piezoelectric layerwas formed over the titanium oxide film, and except that the RTA wasperformed in a heating apparatus in which oxygen was flowing instead ofnitrogen at a flow rate of 500 cc/min.

Experiment 1

The relationships between the polarization and the voltage (P-V curves)of the piezoelectric elements of the Example and Comparative Examples 1to 3 were obtained with a ferroelectric tester FCE-1A (manufactured byTOYO) by applying triangular waves of 1 kHz in frequency using anelectrode pattern with φ=400 μm. The results are shown in FIGS. 24 to26. For comparison, the result of the Example is shown in all of FIGS.24 to 26.

As shown in FIGS. 24 to 26, the Example, in which the crystallizationwas performed on the titanium base layer in a nitrogen atmosphere,exhibited a good hysteresis curve, and leakage did not occur. On theother hand, it is shown that leakage occurred in the hysteresis curvesof Comparative Example 1, in which the piezoelectric precursor film wascrystallized in an oxygen atmosphere, Comparative Example 2, in which atitanium oxide film was used instead of the titanium film as the baselayer underlying the platinum film, and Comparative Example 3, in whichan iridium film was formed on the platinum film.

Experiment 2

The relationships between the electric field-induced distortion and theelectric field intensity (S-V curve) of the piezoelectric elements ofthe Example and Comparative Examples 1 and 3 were obtained at roomtemperature with a double-beam laser interferometer (DBLI) manufacturedby aixACCT by applying a voltage of 1 kHz in frequency using anelectrode pattern with φ=500 μm. The results are shown in FIGS. 27 and28. For comparison, the result of the Example is shown in both figures.

FIGS. 27 and 28 show that the Example, in which the crystallization wasperformed in a nitrogen atmosphere, exhibited larger displacement thanComparative Examples 1 to 3, and thus had superior piezoelectriccharacteristics. In addition, it was confirmed that the piezoelectricelement of the Example exhibits a large electric field-induceddistortion, and that it is ferroelectric and has a linearity withvoltage that ferroelectrics do not exhibit.

Experiment 3

The secondary ion mass spectra (SIMS) of the piezoelectric elements ofthe Example and Comparative Example 1 were observed from thepiezoelectric layer 70 in the thickness direction after the secondelectrode was removed. The results are shown in FIG. 29. The left of thefigure is the second electrode side, and the right is the substrateside. FIG. 29 shows that in the Example, in which the piezoelectricprecursor film was crystallized in a nitrogen atmosphere, titanium wasdiffused from the titanium base layer. The diffused titanium segregatedin the platinum layer and the piezoelectric layer. This shows that thetitanium was diffused up to the inside of the piezoelectric layer. Thisresult and the results of Experiment 1 suggest that the insulation ofthe piezoelectric element can be enhanced by diffusing titanium. In theExample, a peak of titanium is present between the platinum layer andthe piezoelectric layer, as indicated by the arrow in FIG. 29. Thissuggests that the second titanium oxide layer was formed in this region.The thickness of the second titanium oxide layer was measured bytransmission electron microscopy (TEM), and the result was 1 nm.

On the other hand, the result of Comparative Example 1 shows that thetitanium in the titanium film underlying the platinum film cannot bediffused by crystallizing the piezoelectric precursor film in an oxygenatmosphere. This result and the results of Experiment 1 suggest that inorder to diffuse titanium to enhance the insulation of the piezoelectricelement, the crystallization of the piezoelectric precursor film isperformed in a nitrogen atmosphere. In Comparative Example 1, a peak oftitanium was not observed between the platinum layer and thepiezoelectric layer, unlike the Example. This suggests that the secondtitanium oxide is not formed in this region.

Experiment 4

The secondary ion mass spectra (SIMS) of the piezoelectric element ofthe Example and Comparative Example 2 were observed from thepiezoelectric layer 70 in the thickness direction after the secondelectrode was removed. The results of the Example are shown in FIG. 30,and the results of Comparative Example 2 are shown in FIG. 31. The leftof the figure is the second electrode side, and the right is thesubstrate side. These results show that in the Example, titanium wasdiffused from the titanium film underlying the platinum film, as inExperiment 3. The diffused titanium segregated in the platinum layer andthe piezoelectric layer. This shows that the titanium was diffused up tothe inside of the piezoelectric layer.

On the other hand, the results of Comparative Example 2, in which atitanium oxide film was formed instead of the titanium film as the baselayer, show that titanium is not diffused even by crystallizing thepiezoelectric precursor film in a nitrogen atmosphere. This suggeststhat in order to diffuse titanium to enhance the insulation, the baselayer is made of titanium.

Experiment 5

The piezoelectric element of the Example and Comparative Examples 1 to 4were subjected to powder X-ray diffraction analysis to obtaindiffraction patterns of the piezoelectric layers at φ=ψ=0° with D8Discover (manufactured by Bruker AXS) using CuKα rays at roomtemperature. The results of the Example and Comparative Examples 1, 2and 4 are shown in FIG. 32, and the result of Comparative Example 3 isshown in FIG. 33 together with the results of the Example andComparative Example 2.

FIGS. 32 and 33 show that the powder diffraction patterns were varieddepending on the atmosphere for RTA, the material of the base layerunderlying the platinum film, and whether or not the platinum film isused for the first electrode, and that only the piezoelectric layer ofthe Example was oriented in the (100) plane. More specifically, only thepiezoelectric layer of the Example exhibited a diffraction spectrum inwhich the area intensity of the peak derived from ABO₃ structuresobserved in 20°<2θ<25° is at least 90% that of the total area intensityof peaks derived from ABO₃ structures observed in 20°<2θ<50°; hence, thepiezoelectric layer of the Example was oriented in the (100) plane. Allthe diffraction patterns of the Example and Comparative Examples 1 to 4showed ABO₃ structure-derived diffraction peaks. This shows that thepiezoelectric layers of the Example and Comparative Examples 1 to 4 haveABO₃ structures.

As shown in FIGS. 32 and 33, the piezoelectric layer of the Exampleexhibited a peak around 2θ=46.1° representing a ferroelectric phase, anda peak around 2θ=46.5° representing an antiferroelectric phase. Thissuggests that the piezoelectric layer of the Example is in amorphotropic phase boundary (MPB) including both structures derived froma ferroelectric and an antiferroelectric.

Experiment 6

The conduction mechanisms of the piezoelectric elements of the Exampleand Comparative Example 1 were examined from their currentdensity-electric field (J-E) plots. FIG. 34 shows the results of tunnelemission mechanisms. These results show that the piezoelectric elementof the Example, in which the crystallization was performed in a nitrogenatmosphere, hardly showed a tunnel current, and suggest that it canreduce leakage current. On the other hand, in Comparative Example 1, inwhich the crystallization was performed in an oxygen atmosphere, atunnel current occurred at the higher electric field side. This isprobably because the oxygen of the oxygen flow acted as a donor to causea tunnel current.

Experiment 7

The relationships between the current density and the voltage (I-Vcurves) of the piezoelectric elements of the Example and ComparativeExample 1 were obtained by applying voltages of ±60 V to thepiezoelectric elements. The results are shown in FIG. 35. These resultsshow that the piezoelectric element of the Example, in which thepiezoelectric precursor film was crystallized by heating in a nitrogenatmosphere, had a higher insulation than that of Comparative Example 1,in which the crystallization was performed in an oxygen atmosphere, andthat the withstand voltage can be also increased.

Other Embodiments

Although an exemplary embodiment of the invention has been described,the invention is not limited to the disclosed embodiment. Although theabove embodiment has described a piezoelectric layer made of anABO₃-type complex oxide having a fundamental composition containingmetallic elements of only Bi, La, Fe and Mn, the piezoelectric layer maybe made of any other ABO₃-type complex oxide and other metals may beadded to adjust the characteristics, as long as it contains Bi, La, Feand Mn.

Although, in the above embodiment, a monocrystalline silicon substrateis used as the flow channel substrate 10, the flow channel substrate 10may be made of, for example, SOI or glass, without particularlimitation.

Although the piezoelectric element 300 of the above embodiment includesthe first electrode 60, the piezoelectric layer 70 and the secondelectrode 80 that are stacked in that order on a substrate (flow channelsubstrate 10), the structure of the piezoelectric element is not limitedto this structure. For example, the invention can be applied to avertical vibration piezoelectric element including layers of apiezoelectric material and an electrode material alternately formed soas to expand and contract in the axis direction.

The ink jet recording head according to the embodiments of the inventionis installed in an ink jet recording apparatus to serve as a part of arecording head unit including a flow channel communicating with an inkcartridge or the like. FIG. 36 is a schematic perspective view of an inkjet recording apparatus including the ink jet recording head.

The ink jet recording apparatus II shown in FIG. 36 includes recordinghead units 1A and 1B each including the ink jet recording head I, andcartridges 2A and 2B for supplying ink are mounted in the respectiverecoding head units 1A and 1B. The recording head units 1A and 1B areloaded on a carriage 3 secured for movement along a carriage shaft 5 ofan apparatus body 4. The recording head units 1A and 1B eject, forexample, a black ink composition and a color ink composition,respectively.

The carriage 3 on which the recording head units 1A and 1B are mountedis moved along the carriage shaft 5 by transmitting the driving forcefrom a driving motor 6 to the carriage 3 through a plurality of gears(not shown) and a timing belt 7. In the apparatus body 4, a platen 8 isdisposed along the carriage shaft 5 so that a recording sheet S being aprint medium, such as paper, fed from a paper feed roller or the like(not shown) is transported over the platen 8.

Although the above embodiment has described an ink jet recording head asthe liquid ejecting head, the invention is intended for any type ofliquid ejecting head, and may be applied to other liquid ejecting headsejecting liquid other than ink. Other liquid ejection heads includevarious types of recording head used in image recording apparatuses suchas printers, color material ejecting heads used for manufacturing colorfilters of liquid crystal displays or the like, electrode materialejecting heads used for forming electrodes of organic EL displays orFEDs (field emission displays), and bioorganic material ejecting headsused for manufacturing bio-chips.

The piezoelectric element of the embodiments of the invention can beapplied to ultrasonic wave devices such as ultrasonic oscillators andultrasonic motors, pressure sensors, and other devices, without beinglimited to the piezoelectric element used in liquid ejecting headsrepresented by an ink jet recording head.

1. A method for manufacturing a piezoelectric element comprising:forming a titanium film containing titanium; forming a platinum filmcontaining platinum on the titanium film; forming a piezoelectricprecursor film containing bismuth, lanthanum, iron and manganese on theplatinum film; crystallizing the piezoelectric precursor film to form apiezoelectric layer by firing the piezoelectric precursor film in anatmosphere of an inert gas; and forming an electrode on thepiezoelectric layer.
 2. The method according to claim 1, wherein theinert gas is nitrogen.
 3. A method for manufacturing a liquid ejectinghead including a pressure generating chamber communicating with a nozzleaperture and a piezoelectric element allowing the pressure generatingchamber to change pressure, the method comprising: forming a titaniumfilm containing titanium; forming a platinum film containing platinum onthe titanium film; forming a piezoelectric precursor film containingbismuth, lanthanum, iron and manganese on the platinum film;crystallizing the piezoelectric precursor film to form a piezoelectriclayer by firing the piezoelectric precursor film in an atmosphere of aninert gas; and forming an electrode on the piezoelectric layer.
 4. Themethod according to claim 3, wherein the inert gas is nitrogen.
 5. Apiezoelectric element comprising: a first electrode including a firsttitanium oxide layer containing titanium oxide, a platinum layercontaining platinum formed above the first titanium oxide layer, and asecond titanium oxide layer containing titanium oxide formed above theplatinum layer; a piezoelectric layer which contains bismuth, lanthanumiron magnesium and which formed above the second titanium oxide layer;and a second electrode formed above the piezoelectric layer.
 6. Thepiezoelectric element according to claim 5, wherein the piezoelectriclayer contains a complex oxide expressed by general formula (I):(Bi_(1-x),La_(x))(Fe_(1-y),Mn_(y))O₃  (1) wherein x and y satisfy therelationships 0.10≦x≦0.20 and 0.01≦y≦0.09.
 7. The piezoelectric elementaccording to claim 5, wherein the piezoelectric layer exhibits a powderX-ray diffraction pattern obtained at φ=ψ=0° in which the area intensityof the peak derived from ABO₃-type structures observed in 20°<2θ<25° isat least 90% that of the total area intensity of peaks derived fromABO₃-type structures observed in 20°<2θ<50°.
 8. A liquid ejecting headcomprising the liquid ejecting head according to claim
 5. 9. A liquidejecting apparatus comprising the liquid ejecting head according toclaim 8.